Anti-monarchy campaigners walked into Buckingham Palace as paying ticket-holders on Monday morning and unfurled a banner in the Throne Room showing Andrew Mountbatten-Windsor next to Jeffrey Epstein, with the words, "What did you know?"
The protest, staged by the group Republic during the public opening of the State Rooms, was aimed at King Charles and Prince William, GB News reported.
"Republic activists have taken questions about Andrew to the heart of the royal household, the symbolic home of the monarchy," said Graham Smith, speaking for the group.
Republic demanded to know how much the King and the Prince of Wales knew about the allegations against Andrew, and when.
"It is simply not believable to think that Charles and William weren't briefed years ago about the numerous allegations against Andrew," Smith said. "This question isn't going away."
Smith argued that intelligence agencies, police and government ministers would have raised concerns about Andrew's conduct with Palace officials, given the national security and blackmail risks. The group is also exploring a private prosecution against him.
"The monarchy survives on secrecy, and that secrecy has to stop," Smith said.
Andrew was arrested in February on suspicion of misconduct in public office, becoming the first senior British royal arrested in nearly 400 years. He was released the same day and remains under investigation. He has not been charged and denies all wrongdoing.
The arrest followed the Justice Department's release of Epstein files that appeared to show Andrew sharing confidential material with the financier while serving as Britain's trade envoy. The DOJ's handling of those files has since been challenged in federal court as survivors have spent years fighting the secrecy around Epstein's network.
Public feeling toward Andrew has collapsed.
A YouGov survey in April found 93% of Britons hold a negative view of him, including 85% who are "very negative." Just 3% view him positively, his joint-lowest rating on record. YouGov also found that 82% support removing him from the line of succession, and 58% believe the royal family reacted too slowly to the revelations about his relationship with Epstein.
The institution has taken damage too. In polling conducted in March and published last month, support for the monarchy fell to 55%, the lowest Ipsos has recorded since it began asking in 1993. Among Britons aged 18 to 34, just 33% back a monarchy while 45% would prefer a republic.
Charles said after the arrest that "the law must take its course," and the Palace pledged full cooperation. The Prince and Princess of Wales said through a Kensington Palace spokesman that they were "deeply concerned" by the continuing revelations from the Epstein files, and that their thoughts remain with the victims.
Smith said the protest was timed to support Green MP Sian Berry, who is raising the matter of royal exemptions from freedom of information rules in Parliament this week.
Police are now preparing to interview relatives of Epstein's victims in the United States.
